Implantable drug delivery devices are commonly used to provide site specific and/or sustained delivery of beneficial agents to address adverse patient conditions. The pumps are used for the continuous medication delivery over relatively long periods of time in patients who could otherwise only be treated by injecting the medications, such as, e.g., morphines, heparins and similar drugs, several times daily. Pumps are advantageous in comparison with injections in that an even flow rate and a significantly lower total intake of the drug can be realized.
Implantable drug pumps typically include a reservoir for storing a fluid, such as a drug, and a pump or other flow control device to deliver the fluid to a site within a patient. A septum is formed on the top of the pump to allow refilling of the reservoir. Most implantable pumps also include a bolus port which is coupled to the catheter to enable a one-time injection directly to the treatment site. In use, the pump is disposed in a subcutaneous pocket in the area of the abdomen of the patient whereby the refill opening sealed by the septum is palpable under the skin of the patient. The medication reservoir is filled by piercing the skin of the patient and the septum with the corresponding needle of a syringe.
While implantable pumps have been proven to be highly effective, one disadvantage of current designs is the inability to detect leaks in the catheter extending from the pump to the drug delivery site, or between the catheter and the outlet port. Currently, leak detection requires the drug to be removed from the drug reservoir, and sodium chloride to be introduced through the refill port. The pump is then set to dispense the sodium chloride until any residual drug is removed from the reservoir. This process alone can take several days to complete. Once the reservoir is emptied, a contrast agent can then be introduced through the bolus port. An x-ray image of the contrast agent flowing through the catheter is then taken to detect any leaks.
Accordingly, there is a need for improved drug pumps, and for methods for detecting leaks in a drug pump.